Most new aromatics complexes are designed to yield benzene and para-xylene. Benzene is a versatile petrochemical building block used in many different products including ethylbenzene, cumene, and cyclohexane. Para-xylene is also an important building block primarily for the production of polyester fibers, resins, and films formed via terephthalic acid or dimethyl terephthalate intermediates. Since the relative yield of benzene and para-xylene generally does not match the proportions obtained from aromatics-generating processes such as catalytic reforming and cracking, an aromatics complex to obtain these preferred products usually comprises a variety of processes such as one or more of transalkylation, disproportionation, isomerization and dealkylation.
An aromatics complex flow scheme illustrating the use of processes for aromatics conversion is exemplified by Meyers in the Handbook of Petroleum Refining Processes, 3rd. Edition in 2003 by McGraw-Hill.
The known art includes a variety of catalysts effective for converting aromatic feedstocks to desired products. In particular, catalysts have been disclosed for transalkylation to convert lighter aromatics, particularly toluene, and heavier aromatics, especially C9 aromatics, to yield C8 aromatics in order to increase the yield of para-xylene from an aromatics complex. Such transalkylation processes generally are limited in the extent to which they can convert aromatics heavier than C9 to lighter products, and there is a need in the industry for more effective catalysts.